Writes bytes from a buffer to a file or socket.
    The $QIO equivalent is the IO$_WRITEVBLK function.
    Format
      #include  <unixio.h>
      int write  ( int d, void *buffer, int nbytes );

1  –  Arguments

 d
    A descriptor that refers to a socket or file.
 buffer
    The address of a buffer from which the output data is to be
    taken.
 nbytes
    The maximum number of bytes involved in the write operation.

2  –  Description

    This function attempts to write a buffer of data to a socket or
    file.
    Related Functions
    See also socket().

3  –  Return Values

    x                  The number of bytes written to the socket or
                       file.
    -1                 Error; errno is set to indicate the error.

4  –  Errors

    EPIPE              The socket is shut down for writing or is
                       connection oriented, and the peer is closed or
                       shut down for reading. In the latter case, if
                       the socket is of type SOCK_STREAM, the SIGPIPE
                       signal is generated to the calling process.
    EWOULDBLOCK        The NBIO (nonblocking) flag is set for the
                       socket descriptor, and the process is delayed
                       during the write operation.
    EINVAL             The nbytes argument is a negative value.
    EAGAIN             The O_NONBLOCK flag is set on this file, and
                       the process is delayed in the write operation.
    EBADF              The d argument does not specify a valid file
                       descriptor that is open for writing.
    EINTR              A write() function on a pipe is interrupted by
                       a signal, and no bytes have been transferred
                       through the pipe.
    EINVAL             On of the following errors occurred:
                       o  The STREAM or multiplexer referenced
                          by d is linked (directly or indirectly)
                          downstream from a multiplexer.
                       o  The file position pointer associated with
                          the d argument was a negative value.
    EPERM              An attempt was made to write to a socket of
                       type SOCK_STREAM that is not connected to a
                       peer socket.
    EPIPE              An attempt was made to write to a pipe that
                       has only one end open.
                       An attempt was made to write to a pipe or FIFO
                       that is not opened for reading by any process.
                       A SIGPIPE signal is sent to the process.
    ERANGE             An attempt was made to write to a STREAM
                       socket where the value of nbytes is outside
                       the specified minimum and maximum range, and
                       the minimum value is nonzero.